Apparatus for thermostatic control of electric circuits



June 10, 1930.

E. F. HOLINGER APPARATUS FOR THERMOSTATIC CONTROL OF ELECTRIC CIRCUITS Filed April 13, 1928 AT TORNEY Patented June 10, 1930 UNITED STATES PATENT OFFICE EMIL F. HOLINGER, 01 NEW YORK, N. Y., ASSIGNOB TO HUDSON ELECTRICAL HEATING CORPORATION, 01" NEW YORK, N. Y., A CORPORATION OF NEW YORK APPARATUS FOR THERMOBTATIC CONTROL OF ELECTRIC CIRCUITS Application filed April 13, 1928. Serial No. 269,730.

This invention relates to a novel and positively operated mechanical movement and its special application to the operation of circuit controlled apparatus thermostatically actuated. It comprises a vibrating member actuated by variations in temperature and carrying or connected to a pair of oppositely disposed spring pawls between which is located a ratchet wheel so that on the vibration of the thermostat member in one direction, the ratchet wheel is rotated to a predetermined extent, at least equal to on half of the distance between two successive teeth and, on the vibration of the memher in' the opposite direction, a similar movement is given to the ratchet wheel in the same direction. The best form of appa ratus at present known to me embodying my invention is illustrated in the accompanying sheet of drawingsin which Fig. 1 is a side view and partial central section of the apparatus on a small scale, as applied to a boiler.

Fig. 2 is a central section on a larger scale.

Fig. 3 is a top view with the cover removed and parts broken away in section.

Fig. 4 is a detail plan View of the ratchet wheel showing the vibrating member in two positions, and

Fig. 5 is a section on line 5-5 of Fig. 2,

with parts broken away.

Throughout the drawings like reference characters indicate like parts.

Referring to Fig. 1, a boiler or hot water heater is shown at 1, heated by any suitable device such as the gas burner 2. A control apparatus for the burner is shown at 3, which in the case illustrated would be an electrically operated valve actuated by ourrent in the circuit 4 from the source of supply 5. A cylindrical cu 6.is screwed into the side of the boiler, orminga chamber for the reception of the heat-actuated portion f the thermostat, generally represented at 40. .This thermostat would comprise a circuit controller for circuit 4, so that when the temperature in the water of the boiler reached a predetermined dpoint, the gas control 3 would be operate to turn down or turn off the supply of gas to the burner 2.

The thermostatic apparatus, as illustrated in Figs. 2 to 5, comprises the tubular container 7, containing the base block 8, held in place by setscrew 9, in which block is fastened the flexible member 10 composed of two metals of different coefficients of expansion and contraction under temperature variations, as shown. This bi-metallic strip is held in block 8 by pins 11, 11. The cylindrical container 7 has a threaded enlarged portion 7 a at one end which maybe screwed into the mouth of the thermostatic chamber 6 by means of a wrench applied to the hexagonal boss 7 on said container.

12 is a casing for the mechanical movement and circuit controller operated there-.

by, said casing being mounted on theopen end of the container 7 and having a central opening 13 through which the bi-metallic strip 10 projects into the casing interior. 14 is a cover for casing 12.

In the casing is the block 15 mounted on horizontally extending guide pin 18. In this block the end of the bi-metallic strip 10 is held by setscrew 15. Pawl members 16, 16, flexible toward and from one another, are fastened on the edges of block 15 'by setscrews 17, 17. The ratchet wheel 41 having a given number of teeth is supported between these pawls on the journal pin 28, screwed into bracket 29 which is supported from the side of the casing 12 by fastening screw 30. Obviously, as the flexible'member 1O vibrates from right to left, lookin at Fig. 2, the pawls 16, engagin ratchet w eel 41, will rotate it intermlttent y in one direction, giving it a step-by-step motion, if the amplitude of vibration of the pawls equals at least one half the distance between two teeth. Guide pin 18 ismo able horizontally in the sleeve 19, screwed into housing 20 supported from the side of casing 12 by fastening screw 21. This housing at its free end is bifurcated, producing the slight- 1y flexible jaws 22, 22, which can be forced together by screw 23 so that when the position of the sleeve 19 has been properly adjusted, it can be then clamped in that posis tion by setting up on screw 23. A nut 24, on the threaded, free end of guide pin 18,

is provided with the circular boss 24*, and the sleeve 19 has a similar boss 19*, on its free end, so that on and between these two bosses a spiral compression spring 25 may be mounted. sleeve 19 by which it may be screwed in or. out to adjust its position in housing 20. With the above described apparatus the tension on spring 25 can be so adjusted by turning the nut 24 that the block 15 and pawls 16, 16, can not move until the tension on the thermostat element 10 exceeds a predetermined amount. 26 is a threaded cover which may be removed from an aperture in the side of casing 12 in line with guide pin.

18 in order to give access to nut 24 for the purpose of rotating same.

The circuit breaking device operated by the intermittent rotation of ratchet wheel 41 may be of any desired form. I have shown a toothed wheel 27 made of non-conducting material, such as indurated fibre, mounted on journal pin 28 and rigidly connected to ratchet wheel 41 by the intervening spacing member 42. This toothed wheel 27 has twice as many teeth 27" as has ratchet wheel 41, every alternating one of which teeth has a facing 31 of conducting material, such as brass. 32 is an annular conducting plate on the upper face of toothed wheel 27, which plate is electrically connected to all of the conducting teeth facings 31. A spring contact member 33, bears on plate 32 and is mounted on the threaded bolt 35 and insulated from casing 12 by insulating sleeve the casing for clamping the wires of the electric circuit, such as 4, thereto and establishlng connections to the respective contacts from said circuit. The contact members are held on the bolts by nuts 39 placed inside of the casing 12.

The operation of the above described embodiment of the invention is as follows: Spring 25 is so adjusted with reference to the predetermined pull to be given by the bimetallic member 10 that no motion of block 15 and pawls 16 to the left (looking at Fig. 2) will occur until the temperature in the boiler has reached a predetermined point. Thereafter a slight further rise of temperatwo will produce a positive movement to the left of the pawls 16 which will produce gradual rotation of ratchet 41 and toothed wheel 27, moving the conducting face of a tooth along under contact member 34 which is resting on' it, as shown in Fig. 3. As the conducting face of this tooth is in contact with 19 is a hexagonal boss on.

plate 32 at all times the electric circuit 4,

of pawls 16 to the left has rotated wheel 27 far enough (a distance of one tooth) to cause spring contact 34 to snap over the end of the tooth on which it rests, and come to a bearing on the succeeding tooth 27,.wh1c h has then been moved up under it. This breaks the circuit, as the next tooth has no conducting face, and, in the arrangement shown, would extinguish or turn down the gas burner 2 with the result that the water in the boiler would not be further heated and would eventually begin to cool down. This permits the bi-metallic member 10 to graduall move back toward the right under pull of t e spring 25 with the result that the other spring pawl 16 would engage a tooth in front of it on the other side of the wheel 41 and continue the rotation of said toothed wheel 27 in the same direction (a distance of another tooth), until the spring contact member 34 snapped over the edge of the nonconducting tooth 27 on which it was resting and down onto the next tooth, which is provided with a conducting facing 31, thus closing circuit 4, turnin on or turning up the burner 2 and resuming the heating of the water in the boiler.

The rear faces of all the teeth on wheel 27 are undercut, as shown at 43, so that whenever the spring contact 34 rides over the apex of any one of these teeth it flexes down on the next tooth .without dragging over the rear face of the tooth which it is leaving. This gives an instantaneous break or closure and avoids sparking. By so adjusting the parts that a temperature of 200 degrees Fahrenheit, for example, will be necessary to produce enough flexing force in the member 10 to begin the further compression of spring 25, and so proportioning the teeth on the ratchet wheel 41 and toothed wheel 27 that the flexure of the member 10 produced by a further rise of 10 degrees in temperature will cause the contact member 34 to ride over the apex of a tooth, and the other spring pawl 16 to act similarly on said ratchet wheel 41 on the return movement of member 10, it is evident that the variations in temperature in the boiler can be confined between 200 and 210 degrees Fahrenheit. By otherwise adjusting and proportioning the parts the zone of permissible temperature variations in the boiler may be varied accordingly, both as to extent and location.

Among the advantages of the invention may be mentioned compactness of the apparatus, its positive action in responding with equal certainty to temperature increases or decreases, its freedom from sparking and from any liability to burn out contacts, and the ease of adjustment for different zones of temperature variation by merely adjusting rut 24.

determined rise of temperature.

While I have illustrated the invention as.

applied to boiler heat control, it could be easily adapted to other heat controls b those skilled in the art and other forms of t ermostat actuating member could be substituted for the bi-metallic strip 10 here shown.

In Fig. 4 the block 15, carried by vibrating thermostat member 10, is shown in one position in full lines and in another position in dot-and-dash lines to illustrate its movement with reference to ratchet wheel 41, which is mounted in fixed journal pin 28 (not shown in Fig. 4). A partial rotation of ratchet wheel 41, such as would be caused by movement of block 15 to its dot-and-dash line position, is also indicated by showing a few of its ratchet teeth in dot-and-dash llnes.

The preferred method of adjusting the parts is to first so locate guide sleeve 19 in ousing 20 that block 15 will just touch the end face of guide 19 when strip 10 is in the position occupied at' room temperature. Then by turning nut 24 ring 25 is compressed to the extent foun necessary by experiment to hold block 15 in such contact until the predetermined lower limit of'temerature in the boiler has been reached. To

x the upper limit of temperature, i. e. that at which t e circuit will be broken, the space between ratchet wheel teeth must be such that a movement of the pawls equal to half that distance will be produced by the pre- This result is evidently a function of several factors such as the construction of strip 10, length of pawls 16, diameter of ratchet wheel 41, and number of teeth on it, as those skilled in the art'will readily understand.

The reason why a vibration of pawls 16 to the left (looking at Fig. 4) equal to half the distance between any two ad acent teeth of ratchet wheel 41 will cause the then nonacting pawl 16 to engage another tooth so as to continue the turning of the ratchet wheel on the return half of the vibration a sufiicient distance to complete a partial revolution of one tooth of wheel 41 for each complete vibration of the pawls, is that while the lower pawl 16 (looking at Fig. 4) is moving to the left a space of half a tooth the wheel is itself turning so that the tooth under this lower pawl is moving a half space to the right. Consequently 'a vibration of both awls through only half a tooth space ena les the lower pawl to engage the next tooth for the return movement, whichthe vibration of said pawl through exactly one halt of a tooth space, and doesnt hang on the point of the tooth then moved under and the pawl cannot hang on the point of the'tooth without slipping behind it. Consequently each reverse movement of the pawls will start a further step movement of the ratchet wheel, and not merely result in a pawl sliding back over the face of the tooth along which it has theretofore moved during the preceding half vibration or step movement. Any such failure to completely engage the next tooth would, of course, result in only half a complete cycle of circuit controller operations, which might thereafter leave the circuit open or closed indefinitely in spite of subsequent movements of the thermostat member 10.

The vibration of the pawls may be limited to the exact extent necessary to cause them to engage the nexttooth on each cycle of operations by means of the ad'ustable screw stop 43, which can be fixed 1n the proper position by lock nut 44, but the use of such a stop is not always necessary.

Having described my invention, I claim:

1. In a thermostat for controlling electric circuits the combination of a member adapt ed to be reciprocated by chan es in temperature, a pair of oppositely isposed pawls adapted tobe moved simultaneously by said member, a ratchet wheel which is located between said pawls and engaged thereby, and circuit closing and breaking apparatus adapted to be actuated by the rotation of said ratchet wheel.

2. Acombination such as defined in claim 1 in which said member adapted to be reciprocated by changes in temperature comprises a flexible strip formed of two metals aving different coefiicients of expansion and contraction under temperature variations rigidly mounted at one end and carrying said pawls at its free end.

'3. In a thermostat for controlling electric circuits the combination of a member adapted to be reciprocated by changes in temperature, a pair of oppositel disposed pawls adapted to be moved simultaneously by said member, a ratchet wheel which is located between said pawls and engaged thereby, and circuit closing and breaking apparatus adapted to be actuated by the rotation of said ratchet wheel comprisin a toothed wheel having an even number 0 teeth faced alternately with conducting and non-conducting materials, a spring contact member adapted to bear on the faces of said teeth and adapted to be connected to one terminal of an electric circuit, and means for maintaining the other terminal of said circuit continuously in electrical connection with all conducting tooth facings; whereby when said toothed wheel is rotated intermittently in one direction by said temperature actuated member, said spring contact member is thereby brought to bear alternately on conducting and non-conducting teeth to close and open said circuit.

4. A combination such as defined in claim 8 in which said conducting and non-conducting teeth are all undercut on their rear faces, whereby said pawl snaps quickly from each tooth to the next, as the toothed wheel is rotated.

5. A combination such as defined in claim 3 in which said toothed wheel is made of non-conducting material and has a conducting plate mounted on one side thereof and electrically connected to all said conducting tooth facings, and a spring contact adapted to be connected to one circuit terminal hearing on said plate.

6. In a thermostat for controlling electric circuits the combination of a flexible strip formed of two metals having difierent coeflicients of expansion and contraction under temperature variations rigidly mounted at one end and carrying two oppositely disposed pawls at the other end flexible toward and from one another laterally of said strip, a ratchet wheel which is mounted on an axis substantiall parallel with the longer dimensions 0 said strip and located between and engaging both said pawls, and circuit closing and breaking aparatus adapted tobe progressively operated in one direction by the rotation of said ratchet wheel.

7. A structure such as defined in claim 6 combined with an adjustable spring adapted.

to exert pressure on one face of said flexible strip and prevent movement thereof in the direction resulting from a rise of temperature until such rise in temperature exceeds a predetermined amount.

8; A structure such as defined in claim 6 combined with an adjustable spring adapted to exert pressure on one face of said flexible strip and prevent movement thereof in the direction resulting from a rise of temperature until such rise in temperature exceeds a predetermined amount and a ri id abutment on the other side of said flexi le member against which it rests lightly at atmospheric temperature when said spring pressure is released, whereby a circuit may be broken when the temperature rises a predetermined amount above a fixed limit, and be closed when it falls again to such limit.

9. A combination such as defined in claim 6 in which the tooth on aging face of each of said pawls is incline at an angle to the line of flexure of said pawl toward and from said ratchet wheel.

10. In a thermostat for controlling electric circuits the combination of a flexible strip formed of two metals having different coefficients of expansion and contraction under temperature variations rigidly mounted at one end and carrying two oppositely disposed pawls at the other end flexible toward and from one another laterally of said strip, a ratchet wheel which is mounted on an axis substantially parallel with the longer dimensions of said strip and located between and engaging both said pawls, and circuit closing and breaking apparatus adapted to be progressively operated in one direction by the rotation of said ratchet wheel comprising a toothed wheel of non-conducting material rigidly mounted on the same shaft on which said ratchet wheel is rigidly mounted and having an even number of teeth, each alternate tooth being faced with conducting material, a plate 'of conducting material mounted on one side of said wheel and connected to all said conducting tooth-facing)? a yielding contact member adapted to connected to one terminal of an electric circuit and bearing on the faces of said teeth, and a second contact member ada ted to be connected to the other terminal 0 such circuit and bearing on said conducting plate.

11. A combination such as defined in claim 10 in which the rear faces of all said teeth are undercut.

12. A circuit controller adapted to be operated consecutively in one direction by an intermittently acting apparatus, which circuit controller comprises, in combination, a wheel having an even number of teeth'every other one of which has a conducting face while the others have non-conductin faces, a yielding contact member adapte to be connected to one terminal of a circuit and to bear on said tooth faces, and a second contact member ada ted to be connected to the other terminal 0 such circuit and maintained in electrical connection with all said conducting tooth faces.

".13. A combination such as defined in claim 12 in which all said teeth have their rear faces undercut. I

14. The combination of a ratchet wheel rigidly mounted on a rotatable member, a pair of pawls engaging diametrically opposite teeth on said wheel, means for reciprocating said pawls simultaneously, a wheel having twice as many teeth as said ratchet wheel rigidly mounted on the same member, a conducting face on every alternate tooth of said latter wheel, non-conducting faces on its other teeth, a spring contact member adapted to press on the face of each of said teeth progressively as the wheel is rotated,

and an independent electrical connection to all of said conducting tooth facin 15. A combination such as define in claim 14 in which said means for reci rocating said pawls is adjusted to vibrate t rough a distance equal to at least one half the distance between the teeth of said ratchet wheel.

16. A combination such as defined in claim 14 in which all of the teeth on said second wheel have their rear faces undercut.

17. The combination of a ratchet wheel rigidly mounted on a rotatable member, a pair of pawls en aging diametrically opposite teeth on sai wheel, means for recipro eating said pawls simultaneously, a wheel having twice as many teeth as said ratchet wheel rigidly mounted on the same member, a conducting face on every alternate tooth of said latter wheel, non-conducting faces on its other teeth, a spring contact member ada ted to press on the face of each of said tee progressively as the wheel is rotated, and an independent electrical connection to all of said conductin tooth facings, comprising a. late of con ucting material on one face 0 said wheel, and a yielding contact member bearing thereon.

18. In a thermstat for controlling electric circuits the combination of a member adapted to be reciprocated by changes in tern erature, a pair of oppositely disposed Eaw adapted to be moved simultaneously y said member, a ratchet wheel which is located between said pawl and engaged thereby, and circuit closing and breaking apparatus ada ted to be actuated by the rotation of sai ratchet wheel, together with an adjustable stop for limiting the ampli- 40 tude of reciprocation of said pawls.

F. 'HOLINGER. 

